Method of hollow ball fabrication

ABSTRACT

A method of manufacturing a hollow sperical object such as a hollow ball bearing wherein two hemispherical sections are united. The sections are formed with hollow centerpoints and with mating tongue and ledge configurations adjacent the outer periphery. Indents are placed at the apex of the hemispheres for alignment in a turning machine. The hemispheres are united at the tongue and ledge and are subjected to an electron beam for welding of the hemispheres to a hollow ball form. Thereafter, the periphery of the sphere is machined and in the preferred embodiment is machined a radial distance sufficient to eliminate the welded step at the junction of the tongue and ledge, as well as to eliminate the indents.

United States Patent 1 Hauser Nov. 20, 1973 METHOD OF HOLLOW BALL 7OTHER PUBLICATIONS FABRICATION W 1d H db k 3 ffth d h 54 e mg an 00section 1 e mon c apter [75-] Inventor. Daniel Hauser, Columbus, Ohioespecially pages and 54184432 [73] Assignee: TRW Inc., Cleveland, OhioPrimary Examiner-J. Spencer Overholser F l M 1 1971 [22] 1 ed ayAssistant ExaminerRichard Bernard Lazarus [21] Appl. No.: 144,757Attorney-Hill, Sherman, Meroni, Gross & Simpson [52] US. Cl. 2 9/l48.4B, 29/463, 29/481, [57] ABSTRACT A method of manufacturing a hollowsperlcal ob ect [51] Int. Cl. B2lh 1/14 such as a hollow ball bearingwherem two hemispheri- [58] Field of Search 29/463, 148.4 B,

29/480 481 482 219/121 EM cal sections are unlted. The sections areformed with hollow centerpoints and with mating tongue and ledgeconfigurations adjacent the outer periphery. Indents [56] ReferencesClted are placed at the apex of the hemispheres for align- UNITED STATESPATENTS ment in a turning machine. The hemispheres are 634,981 10/1899Hil'th 29/148.4 B united at the tongue and [edge and are subjected to an2,804,559 8/1957 Brewer 29/463 X electron beam f welding f thehemispheres to a 3 1 59 et 3 23 B low ball form. Thereafter, theperiphery of the sphere I 96 lgh 2 l1 B is machined and in the preferredembodiment is ma- 3,466,910 9/1969 Carlsen 29/l48.4 B d (1.31 ta t t th3,599,307 8/1971 Campbell et al. 29/148.4 B c me a 9 to 6 8 6 3,660,8805/1972 Glenn 29/463 X Welded Step at the J"nctloln of the tongue andhedge, as

well as to eliminate the indents. FOREIGN PATENTS OR APPLICATIONS757,205 6/1933 France 29/1434 B 4 Chums 6 Drawmg Flgum BALL FABRICATIONBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to hollow spherical objects and to a method of manufacturingtherefor.

2. Prior Art Recent design and operating criteria have emphasized thedesirability of using hollow ball bearings in place of the more normalsolid balls. While such hollow balls have been known to the art for sometime, they are extremely difficult to manufacture with any degree ofprecision. For this reason, the preexisting balls have normally beencustom-manufactured by methods requiring a high coefficient of labor.While it has been suggested to use hollowed hemispherical componentswhich are thereafter joined together as by welding, bonding and thelike, extreme difficulties have arisen with regard to alignment of thehemispheres. Further prior art methods of joining have not alwaysproduced a perfect or even operatingly acceptable joinder.

It has been suggested to groove the opposed faces of the hemispheres soas to increase the sealed or welded surface area. (See for example US.Pat. No. 3,l44,710 to Hollander et al.) While such grooves can alsoserve an aligning function, unless they are perfectly concentric,misalignment can be caused by the grooves. Further, because of the factthat a multiplicity of grooves are used, the weld may be more difficultto achieve and a serrated weld line is produced, which introduces thepossibility of voids at the troughs, which voids would result in aweakness in the joined ball.

SUMMARY OF THE INVENTION My invention overcomes many of thedisadvantages of the prior art methods of manufacturing hollow balls,and provides a method adaptable to mass production machinery.

Initially, I began with two hemispheres which have hemispherical hollowsections at their center providing a peripheral wall. One of thehemispheres has a set back ledge provided circumferentially therearoundat the outer periphery mating with the planar face of the hemisphere.The other hemisphere has a cooperating circumferential peripheral tonguedimensioned to mate with the ledge when the two hemispheres are joinedtogether at their planar faces. Ninety degrees from the planar faces atthe apex of the hemispheres, indents are provided for indexing with arotating tool carried projection. The mating tongue and ledge providefor perfect alignment of the hemispheres, while the indents allow thejoined ball to be gripped on opposing points for rotation in a fashionwhich will maintain the main joinder line in a given plane. Thereafter,the joined ball is subjected to an electron beam and is rotated withrespect to the beam source to expose the entire circumference of theball in the area of the joint to the beam. This results in a good weldalong the joinder line.

In the preferred embodiment, after welding and further treating ifdesired, the periphery of the ball is machined to a point where asufficient amount of material is removed to eliminate the indents.Further, in a preferred embodiment, the tongue and ledge are maintainedradially narrow so that the machining process will remove material to asufficient radial depth to eliminate that portion of the ball which,prior to welding, constituted the tongue and ledge.

It is therefore an object of this invention to provide an improvedmethod of manufacturing hollow ball bearings.

It is a further and more specific object of this invention to provide amethod of manufacturing hollow ball bearings wherein a cooperating ledgeand tongue are provided on complimentary hollowed hemispheres to alignthe hemispheres.

It is a further object of this invention to provide a hollow ballbearing having hemispheres joined together by an electron beam weldingprocess.

It is yet another and more specific object of this invention to providea method of manufacturing hollow spherical objects from complimentaryhemispheres, wherein one of the hemispheres has a circumferential ledgeat its planar surface and the other hemisphere has a circumferentialtongue cooperating with the ledge to index the hemispheres togetheralong their opposed planar surfaces, the hemispheres being joined by awelding process.

It is yet another and more specific object of this invention to providea method of manufacturing hollow spherical objects from hemisphereswherein indents are provided at the apex of the hemispheres to providediametrically opposed machined gripping points when the hemispheres arejoined, the indents being machined away after joinder of thehemispheres.

It is yet another and most specific object of this invention to providea method of manufacturing a hollow spherical object from complimentaryhemispheres wherein one of the hemispheres has an outer diameter ledgewhich mates with a circumferential projection on the other hemisphere,the hemispheres being welded together and the resultant ball thereaftermachined to remove material to a sufficient radial depth to eliminatethe area which comprised the tongue and comple mentary ledge.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantagesof the invention will be readily apparent from the following descriptionof a preferred embodiment thereof, taken in conjunction with theaccompanying drawings, although variations and modifications may beeffected without departing from the spirit and scope of the novelconcepts of the disclosure, and in which:

FIG. 1 is a perspective view partially in section of a hollow ballbearing according to this invention.

FIG. 2 is a cross-sectional view of a hollow hemispherical ball sectionhaving a ledge at the periphery thereof.

FIG. 3 is a view similar to FIG. 2, illustrating the opposedhemispherical sections having a ledge dimen sioned to mate with thetongue.

FIG. 4 is a cross-sectional view of a hollow ball comprised of thehemispheres of FIGS. 2 and 3 joined together, illustrating machinealignment indents.

FIG. 5 is a fragmentary cross-sectional view illustrating the effect ofthe electron beam welding step of this invention.

FIG. 6 is a cross-sectional view ofajoined hollow ball manufacturedaccording to this invention, after machining.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a hollow ballbearing 10 which consists of a continuous spherical circumferential wall11 having a hollow interior 12.

Such ball bearings have considerable advantages in certain situationsover solid bearings, including advantages derived from mass reductionand correspondent inertial reduction. It has been found that such hollowbearings operate for longer periods of time under increased heatconditions, as well as being advantageous in other situations.

This invention provides a method of manufacturing such hollow bearings.The method commences with two hemispherical sections 13 and 14illustrated in FIGS. 2 and 3.

The hemispherical section 13 illustrated in FIG. 2 comprises ahemispherical section 13a of the peripheral wall 11 and a hemisphericalsection 13b of the hollow center 12. The planar face 15 defining thebase of the hemisphere has a reduced central portion 16 which defines anouter diameter circumferential tongue 17 projecting at a right angle 18from the planar face reduction 16.

The other hemispherical section 14 illustrated in FIG. 3 comprises acomplementary hemispherical wall section 14a and a complementaryhemispherical hollow center 14b. The base of the hemisphere is definedby a planar face 19, and has an outer diameter circumferential rightangle reduction area defining a ledge 20 having right-angle faces 21 and22 with the face 22 parallel to the face 19. The face 23 of the tongue17 is also parallel to the face 16 of the reduction area of the planarface 15 of the section 13.

The ledge 20 provided by the reduction has a dimension co-extensive withthe tongue 17. As can be seen from FIG. 4, when the two hemispheres arebrought together with the planar face 19 abutting the planar face 16,the tongue 17 will fully extend into the ledge 20 with the face 23 ofthe tongue abutting the face 22 of the ledge, and the inner diameter ofthe tongue abutting the face 21 of the ledge 20. Thus, when the twohemispheres are joined together in face-to-face relation, a hollowsphere is created. Through the use of the indexing tongue and ledge, asphere is assured which has a defined hollow interior with a continuousradius. Without the indexed tongue and ledge, it would be difficult tomate the two hemispheres with perfect indexing of the hollow interior.Absent a perfect indexing of the hollow interior, when a joined-togetherball was machine finished on the exterior, there would be anout-of-balance condition created by the offset of one interior diameterwith respect to the other interior diameter of the two hemispheres. Thiswould create an erratically balanced ball which would either fail orallow the causation of extreme damage to the unit in which it is used.

As illustrated in FIG. 4 in the preferred embodiment, indents 25 areformed at the apex of the hemispheres 13 and 14. The indents take theform of small blind openings precisely centered at the apex of thehemisphere. These form positioning points for the gripping members of aturning machine so that the assembled ball can be turned precisely on anaxis normal to the plane of the mating faces of the hemispheres.

After the hemispheres have been assembled together, the resultant ballis mounted in a turning machine and is subjected to an electron beam androtated thereunder to weld the two hemispheres together. By means of theuse of an electron beam welding procedure, a continuous weld can beassured from the inner diameter 26 of the hollow ball to the outerdiameter 27 thereof, as is illustrated in FIG. 5 where the cross hatch28 is intended to signify a complete weld through the area illustratedby the broken line 29 indicating where the hemispheres were joined priorto welding.

Although FIG. 5 illustrates a 100 percent depth penetration weld, it maybe desirable in certain circumstances to limit the weld to approximatelypercent of the depth so as to prevent the formation of any flash on theinner diameter. Further, the preferred embodiment has been described asbeing welded by an electron beam. However, it is to be understood thatother methods may be utilized such as inertial welding, diffusionbonding, or the like.

After welding the hemispheres, the outer diameter is machined to providethe finished ball. Such a machined ball is illustrated in FIG. 6,wherein neither the inner diameter 26 nor the outer diameter 27 have anyindication of where the joinder line was. This is a preferredembodiment, and the dotted line 28 indicates where the joinder was.During the machining operation, a sufficient depth of the outer diameteris removed to reduce the outer diameter to a point less than the face 21of the ledge 20. In this manner, the entirety of the tongue and ledgeconfiguration has been removed along with the alignment indents 25.

Although the indents 25 are illustrated as being point pricks, it is tobe understood that other configurations may be used such as flat spotsor bulges or the like.

It will be seen from the above that my invention provides a method ofmanufacturing a hollow sphere from mating hemispheres wherein one of thehemispheres carries an outer diameter tongue projecting from its planarface and the other hemisphere has a mating outer diameter reductionledge at its planar face, the tongue and ledge indexing to align theinner and outer diameters of the hemispheres to a sphere configuration.In the preferred embodiment, surface interruptions are provided at theapex of the hemispheres to align the hemispheres in a rotating machineand the assembled sphere is subjected to a welding operation to bond thehemispheres together. Thereafter, the resultant sphere is machined onits outer diameter to a sufficient depth to remove the material from theouter diameter to reduce the outer diameter to a point less than theoriginal ledge point.

Although I have herein set forth my invention with respect to certainspecific principles and details thereof, it will be understood thatthese may be varied without departing from the spirit and scope of theinvention as set forth in the hereunto appended claims.

I claim as my invention:

1. A method of manufacturing a hollow ball bearing comprising: the stepsof forming a pair of hemispheres having central cavities, thehemispheres having equal inner diameters and equal outer diameters witha planar face formed between the inner and outer diameters, forming anouter diameter tongue on one of the hemispheres, the tongue extending ata right angle from the planar face of the hemisphere, forming an outerdiameter reduction ledge on the other of said hemispheres, the saidledge formed at the juncture of the planar face and the outer diameter,the said ledge and tongue having coextensive dimensions, joining the twohemispheres together at the planar faces with the tongue projecting intothe ledge and the inner and outer diameters of the hemispheres aligned,subjecting the resultant sphere to an electron beam welding joiningoperation to join the two hemispheres together permanently at theirplanar faces and machining the resultant sphere to reduce the outerdiameter to a point sufficient to remove the ledge.

2. The method of forming a hollow sphere which comprises the steps ofproviding a pair of hemispheres having equal central cavities forminginner diameters concentric with the outer diameters, forming surfaceinterruptions at the apex of the hemispheres, mating the hemispherestogether at their planar faces, turning the mated hemispheres at leastone revolution while an electron beam is directed at the mating faces ofthe hemispheres to weld them together and using the surfaceinterruptions to hold the hemispheres in alignment with the beam duringturning and machining the outer diameter of the resultant sphere to asufficient depth to remove the surface interruptions.

3. The method of forming a hollow sphere which comprises: the steps offorming a pair of hemispheres with central cavities providing an innerdiameter concentric with and with a planar face therebetween, forming anouter diameter projecting tongue extending at right angles to the planarface of one of the hemispheres, forming an outer diameter reductionledge extending at right angles from the planar face of the otherhemisphere, the ledge and tongue having substantially co-extensivedimensions and opposed planar surfaces, mating the hemispheres togetherwith the opposed planar surfaces in mating relation with one another andthe inner and outer diameters aligned, forming surface interruptions atthe apexes of the hemispheres, rotating the resultant sphere, subjectingthe rotating sphere to a bonding force, and thereafter machining theouter diameter of the bonded-together sphere to remove the surfaceinterruptions while maintaining the outer surface spherical, andcontinuing the machining to a point where the outer diameter has beenreduced to a diameter at least as small as the minimum diameter of theledge.

4. The method of claim 3 wherein the bonding force is an electron beam.

1. A method of manufacturing a hollow ball bearing comprising: the stepsof forming a pair of hemispheres having central cavities, thehemispheres having equal inner diameters and equal outer diameters witha planar face formed between the inner and outer diameters, forming anouter diameter tongue on one of the hemispheres, the tongue extending ata right angle from the planar face of the hemisphere, forming an outerdiameter reduction ledge on the other of said hemispheres, the saidledge formed at the juncture of the planar face and the outer diameter,the said ledge and tongue having coextensive dimensions, joining the twohemispheres together at the planar faces with the tongue projecting intothe ledge and the inner and outer diameters of the hemispheres aligned,subjecting the resultant sphere to an electron beam welding joiningoperation to join the two hemispheres together permanently at theirplanar faces and machining the resultant sphere to reduce the outerdiameter to a point sufficient to remove the ledge.
 2. The method offorming a hollow sphere which comprises the steps of providing a pair ofhemispheres having equal central cavities forming inner diametersconcentric with the outer diameters, forming surface interruptions atthe apex of the hemispheres, mating the hemispheres together at theirplanar faces, turning the mated hemispheres at least one revolutionwhile an electron beam is directed at the mating faces of thehemispheres to weld them together and using the surface interruptions tohold the hemispheres in alignment with the beam during turning andmachining the outer diameter of the resultant sphere to a sufficientdepth to remove the surface interruptions.
 3. The method of forming ahollow sphere which comprises: the steps of forming a pair ofhemispheres with central cavities providing an inner diameter concentricwith and with a planaR face therebetween, forming an outer diameterprojecting tongue extending at right angles to the planar face of one ofthe hemispheres, forming an outer diameter reduction ledge extending atright angles from the planar face of the other hemisphere, the ledge andtongue having substantially co-extensive dimensions and opposed planarsurfaces, mating the hemispheres together with the opposed planarsurfaces in mating relation with one another and the inner and outerdiameters aligned, forming surface interruptions at the apexes of thehemispheres, rotating the resultant sphere, subjecting the rotatingsphere to a bonding force, and thereafter machining the outer diameterof the bonded-together sphere to remove the surface interruptions whilemaintaining the outer surface spherical, and continuing the machining toa point where the outer diameter has been reduced to a diameter at leastas small as the minimum diameter of the ledge.
 4. The method of claim 3wherein the bonding force is an electron beam.